
/**
* URL: https://leetcode.com/problems/h-index/
*
* 题目：
* Given an array of citations (each citation is a non-negative integer) of a researcher, 
* write a function to compute the researcher's h-index.
* According to the definition of h-index on Wikipedia: 
* "A scientist has index h if h of his/her N papers have at least h citations each, 
* and the other N − h papers have no more than h citations each."

 *For example, given citations = [3, 0, 6, 1, 5],
* which means the researcher has 5 papers in total and each of them had received 3, 0, 6, 1, 5 citations respectively. 
* Since the researcher has 3 papers with at least 3 citations each and the remaining two with no more than 3 citations each, 
* his h-index is 3.

* Note: If there are several possible values for h, the maximum one is taken as the h-index.
*/
